Area Forecast Discussion
Issued by NWS Kansas City/Pleasant Hill, MO

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FXUS63 KEAX 210955

National Weather Service Kansas City/Pleasant Hill MO
355 AM CST Tue Feb 21 2017

Issued at 343 AM CST TUE FEB 21 2017

Early morning impacts will reside with the potential for dense fog
as upper-level cloud cover clears from west to east overhead
residual low-level moisture. Areas that have cleared have
undergone sufficient cooling to dewpoint values, with resulting
dense fog quickly developing. For now, this has been limited to
areas across southeastern Kansas, in addition to areas over
southwestern Iowa. Will need to monitor the eastward push of cloud
cover through Tuesday morning before surface temperatures
increase after sunrise.

An upper level low will continue to become detached from the main
flow through the mid-week. The associated moisture band and light
precipitation will exit the forecast area by the mid-morning
hours, with clearing sky conditions prevailing over the next
couple of days. A weak cold front will cross over northwestern
Missouri today before stalling near central Missouri. This will
provide a brief period of northwesterly surface flow before zonal
flow aloft rebuilds over the Central Plains and southwesterly
surface flow returns to the area by the afternoon. With ample
sunshine and a return of warm advection in the wake of the exiting
storm system, temperatures will rebound slightly from yesterday,
climbing into the lower 70s. Southwesterly surface flow will pull
dry air back into the region, and dewpoints will once again dip
into the upper 30s. Fire weather danger will be marginally
heightened today with warming temperatures and decreased relative
humidity values in the upper 20s to lower 30s. However, calm
surface winds will help to minimize the full potential of fire
weather concerns for at least today. Dry southwesterly flow will
persist into Wednesday, with wind gusts expected to approach 20 to
25 mph in response to a tightening PGF as a surface low matures
over the Northern Plains. This will make for the most likely
period of fire weather danger through the week as record-breaking
temperatures are expected to rise into the mid to perhaps upper
70s Wednesday.

By Thursday morning, a cold front will stall across northern
Missouri ahead of a weak shortwave over the Northern Plains. This
will present a sharp thermal gradient with regard to afternoon highs
Thursday, with temps ranging from the upper 50s across northern
Missouri and rising into the upper 60s and lower 70s for areas south
of I-70. Also, a broad upper level trough situated over the western
CONUS will form a surface low over western Kansas during this time.
This feature will lift a warm front into northern Missouri by
Thursday afternoon and will bring the next chance of precipitation
into the area, generally north of I-70, beginning Thursday
afternoon. The attendant cold front will push through
northwestern Missouri early Friday, though limited mid to upper
level moisture ahead of the boundary will maintain chances of
precip closer to the warm front across areas north of I-70.
Additional moisture along the backside of the surface low will
provide a brief period of additional precipitation late Friday
into Saturday over this area. Wintry precipitation is possible
Friday night within a cooling thermal profile, though, with the
exception of extreme northern Missouri, accumulating snowfall is
not anticipated.

Temperatures will remain closer to seasonal values as cold advection
persists over the area through much of the weekend. The relatively
active pattern will then continue with additional chances of
precipitation returning by the early work week.


.Aviation...(For the 06Z TAFS through 06Z Tuesday Night)
Issued at 1131 PM CST MON FEB 20 2017

Front is making its way through the region, currently in the
vicinity of STJ, and is expected to continue its southeasterly
progress through the other three terminals within the next couple
of hours. Look for a wind shift as it passes through, becoming NW
behind it. With clear skies behind the front, and some LL
moisture present (thanks to the showers early Monday), fog
chances still look possible, although the much drier airmass
moving in behind the front could inhibit development. By midday
tomorrow, any fog that would have developed will have dissipated,
allowing for VFR conditions (clear skies) to prevail for the
remainder of the TAF period.


.Fire Weather...
Issued at 357 PM CST MON FEB 20 2017

Fire concerns will be the primary weather issues for Tuesday and
Wednesday as dry air moves in and temperatures warm well above
normal. Afternoon highs will range through the 70s both Tuesday and
Wednesday as a surface ridge slides in behind today`s trough. Mixing
under the ridge will be extensive, and given the dry air seen in
soundings just off the ground, thoughts are that boundary layer
mixing will allow humidity values to bottom out in the 20% range
both Tuesday and Wednesday, with some areas in far northwest
Missouri likely to see humidity values drop into the teens. These
humidity values are well within criteria for critical fire weather
conditions. However, surface winds will not be overly strong Tuesday
thanks to the surface ridge; but that could be different for
Wednesday when the surface ridge slides east allowing a tighter
pressure gradient to prevail, thus stronger winds. Currently,
Wednesday is looking like the worst fire weather day of the week
thus far.




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